The credit field has recently seen the emergence of a type of credit card, often referred to as a "smart" card, which includes in it a semiconductive microcomputer adapted to store and process data (relating, for example, to the identity of the card owner), and which card, moreover, is adapted to have transfer of data take place between the microcomputer therein and circuitry in a complementary card receptor. For a survey discussion on cards of such type, reference is made to the article "Smart Credit Cards: the answer to cashless shopping" appearing on pages 43-49 of the February, 1984 issue of the IEEE Spectrum.
In the past, the interaction between the microcomputer in such cards and the circuitry of the receptor in which the card is inserted has, for the most part, been, effected by electromechanically coupling the microcomputer and such circuitry through an array of pins extending from the receptor into holes formed in the cards to contact elements in the card. That electromechanical mode of interconnecting the card and receptor has, however, the shortcomings of wear of the contacts, accumulation of dirt therein, and possible vandalism thereof (by, say, exposing them to spray paint) to the point where, often after too short a time, the electromechanical connection becomes inoperative.
In an effort to overcome such deficiencies, U.S. Pat. No. 4,480,178 issued Oct. 30, 1984 in the name of R. R. Miller II, et al for "Tuning Arrangement For Interfacing Credit Card-like Device to a Reader System" and assigned to the assignee hereof, and incorporated herein by this reference, discloses an arrangement in which, for purposes of transferring electrical energy from the receptor to a card therein to supply operating power and a clock signal to the microcomputer in the card, the receptor contains two plate members which respectively register in closely spaced relation with a corresponding two plate members in the card so as to form two capacitors electrically coupling the receptor and card. Power is supplied from the receptor to the card by the use of such capacitive coupling. A problem encountered in such mode of coupling the receptor and card is, however, that, because the size of the capacitor plates of the card must necessarily be small in order to fit within the card and make room for the other elements thereof, the capacitance which can be provided by such card plates and the registering receptor plates is also necessarily small so as to result in certain applications in an undesirably low limit on the amount of electrical energy transferrable between the receptor and card.
As an alternative, U.S. Patent application, Ser. No. 664,555 filed Oct. 25, 1984 in the name of R. L. Billings for "Flexible Inductor", and assigned to the assignee hereof, and incorporated herein by this reference, discloses an arrangement in which, for purposes of transferring electrical energy from the receptor to a card therein to supply operating power and a clock signal to a microcomputer in the card, the card includes a flexible coil and a flexible ferromagnetic member adapted upon insertion of the card in the receptor to inductively couple the coil to transformer primary means in the receptor so that the coil will operate as a transformer secondary and, in that role, transfer operating power and the clock signal from the receptor to the microcomputer in the card. No provision, however, is made in such arrangement for transfer of data between the receptor and the microcomputer of the card.